Electrodeposition whetstone and manufacturing method

ABSTRACT

According to an embodiment, an electrodeposition whetstone includes a plating layer, first abrasive grains protruding from the plating layer, and second abrasive grains which are arranged between the first abrasive grains. The amount of protrusion of the second abrasive grains from the plating layer is smaller than the amount of protrusion of the first abrasive grains from the plating layer. A grain size of the second abrasive grains is smaller than a grain size of the first abrasive grains.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCT Application No. PCT/JP2021/027687, filed Jul. 27, 2021 and based upon and claiming the benefit of priority from prior Japanese Patent Application No. 2020-187129, filed Nov. 10, 2020, the entire contents of all of which are incorporated herein by reference.

FIELD

The present invention relates to an electrodeposition whetstone and a manufacturing method thereof.

BACKGROUND

Jpn. Pat. Appln. KOKAI Publications No. 2011-245561, No. H2-145261, and H6-114739 disclose electrodeposition whetstones. In the electrodeposition whetstone of Jpn. Pat. Appln. KOKAI Publication No. 2011-245561, abrasive grains with a larger average grain size and abrasive grains with a smaller average grain size are adhered by a plating layer. An abrasive grain layer containing the abrasive grains with a smaller average grain size is disposed on an outer side of an abrasive grain layer containing the abrasive grains with a larger average grain size. In the electrodeposition whetstone of Jpn. Pat. Appln. KOKAI Publication No. H2-145261, the larger-diameter superabrasive grains and the smaller-diameter superabrasive grains are adhered to the base by a metal plating layer that is a uniformly dispersed single layer. In the electrodeposition whetstone of Jpn. Pat. Appln. KOKAI Publication No. H6-114739, larger-diameter superabrasive grains are supported by an electroless plating layer, and smaller-diameter superabrasive grains are uniformly dispersed in this electroless plating layer.

SUMMARY

According to an embodiment, an electrodeposition whetstone includes a plating layer, first abrasive grains protruding from the plating layer, and second abrasive grains which are arranged between the first abrasive grains. The amount of protrusion of the second abrasive grains from the plating layer is smaller than the amount of protrusion of the first abrasive grains from the plating layer. A grain size of the second abrasive grains is smaller than a grain size of the first abrasive grains.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a cross section of an electrodeposition whetstone according to an embodiment.

FIG. 2 is a schematic view showing steps of an exemplary manufacturing method according to the embodiment.

FIG. 3 is a schematic view showing a cross section of an electrodeposition whetstone according to a modification example of the embodiment.

FIG. 4 is a schematic view showing a cross section of an electrodeposition whetstone according to another modification example of the embodiment.

DESCRIPTION

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a cross section of an electrodeposition whetstone according to this embodiment. The electrodeposition whetstone 1 includes a base 2, a plating layer 3, first abrasive grains 4, and second abrasive grains 5, which differ from the first abrasive grains 4. The base 2 is a base component (base metal) of the electrodeposition whetstone 1, which has conductivity. The base 2 is formed, for example, of a material that contains a metal such as aluminum, iron, or stainless steel, or an alloy thereof. The material of the base 2 is not limited as long as it has conductivity. It is assumed here that the base 2 of the embodiment is shaped into a disk or substantially into a disk. In the electrodeposition whetstone 1, a thickness direction (indicated by arrows D1 and D2) and an orthogonal direction intersecting (perpendicular or substantially perpendicular to) the thickness direction are defined. In the following description, the direction from the base 2 toward the plating layer 3 (indicated by arrow D1) is defined as outward, and the direction opposite to the outward direction (indicated by arrow D2) is defined as inward. The shape of the base 2 can be suitably selected based on the use of the electrodeposition whetstone 1, the type of a grinding workpiece, and the like.

The plating layer 3 is arranged on the base 2. The plating layer 3 includes the first abrasive grains 4 and the second abrasive grains 5. The plating layer 3 holds the first abrasive grains 4 and the second abrasive grains 5. The plating layer 3 may be formed of a nickel-containing material. The thickness of the plating layer 3 is defined by the thickness extending from the outer surface (external surface) of the base 2 to the outer surface (external surface) of the plating layer 3. For instance, the thickness of the plating layer 3 represents an average thickness of the plating layer 3. The thickness of the plating layer 3 can be suitably determined based on the processing conditions such as the use of the electrodeposition whetstone 1 and the type of the grinding workpiece. As described later, the thickness of the plating layer 3 is determined in such a manner that at least part of the first abrasive grains 4 and at least part of the second abrasive grains 5 both protrude (are exposed) from the outer surface of the plating layer 3. For instance, the thickness of the plating layer 3 may be 40% or larger and 80% or smaller of the average abrasive grain size of the abrasive grains 4.

The plating layer 3 includes a first plating layer 31 and a second plating layer 32 different from the first plating layer 31. The first plating layer 31 is provided on the base 2, and the second plating layer 32 is provided on the first plating layer 31. In other words, the second plating layer 32 is stacked on the first plating layer 31. For instance, the first plating layer 31 and the second plating layer 32 may contain nickel. The second plating layer 32 may include particles having a friction coefficient lower than that of the second plating layer 32. The average particle size of these particles can be measured using a commonly used method. For instance, a laser diffraction particle size distribution analyzer may be used for the measurement. In one example, such particles include at least one of polytetrafluoroethylene (PTFE), graphite fluoride, silicon carbide, boron carbide, and tungsten. The particles may also contain nanodiamond particles. Consequently, the friction coefficient of the second plating layer 32 is lowered, which makes the second plating layer 32 resistive to wearing by grinding chips. As a result, the wear resistance of the electrodeposition whetstone 1 is improved. In addition, clogging of the electrodeposition whetstone 1, which tends to be caused by grinding chips, can be suppressed. The second plating layer 32 preferably contains PTFE of an average particle size of 0.1 μm or larger and 1 μm or smaller. With boron or tungsten contained in the second plating layer 32, the hardness (Vickers hardness (Hv)) of the second plating layer 32 increases.

The first abrasive grains 4 and the second abrasive grains 5 can be suitably selected depending on the grinding workpiece and the use of the electrodeposition whetstone 1. For instance, the first abrasive grains 4 and the second abrasive grains 5 are at least one selected from silicon carbide-based abrasive grains, alumina-based abrasive grains, metal oxide abrasive grains, and superabrasive grains. The metal oxide abrasive grains may be zirconium oxide. The superabrasive grains may be diamond abrasive grains and cubic boron nitride (CBN) abrasive grains. Combinations of the first abrasive grains 4 and the second abrasive grains 5 may be: diamond abrasive grains and diamond abrasive grains; CBN abrasive grains and CBN abrasive grains; diamond abrasive grains and metal oxide abrasive grains; CBN abrasive grains and metal oxide abrasive grains; or CBN abrasive grains and diamond abrasive grains. It is preferable that the first abrasive grains 4 be CBN abrasive grains and the second abrasive grains 5 be diamond abrasive grains.

The grain size of the second abrasive grains 5 is smaller than the grain size of the first abrasive grains 4. The grain size of the first abrasive grains 4 (or second abrasive grains 5) indicates, for example, the average grain size of the first abrasive grains 4 (or second abrasive grains 5). The ratio of the grain size of the second abrasive grains to that of the first abrasive grains may stand at 0.4. The grain size of the first abrasive grains 4 may be 25 μm or larger and 300 μm or smaller. The grain size of the second abrasive grains 5 may be 10 μm or larger and 120 μm or smaller. In one example, with the grain size of the first abrasive grains 4 being 25 μm, the first abrasive grains 4 correspond to the grit size 600, and with the grain size of the first abrasive grains 4 being 300 μm, the first abrasive grains 4 correspond to the grit size 50. In another example, with the grain size of the second abrasive grains 5 being 10 μm, the second abrasive grains 5 correspond to the grit size 1500, and with the second abrasive grains 5 being 120 μm, the second abrasive grains 5 correspond to the grit size 120. The shape of the first abrasive grains 4 may be at least one selected from being blocky, semi-blocky, and irregular. The first abrasive grains 4 preferably have a semi-blocky shape. If the abrasive grains have a semi-blocky shape, a new cutting edge is created from a fracture in the cleavage plane existing in the crystal planes of the abrasive grains, thereby suppressing degradation in the grindability of the electrodeposition whetstone 1. The second abrasive grains 5 preferably have a blocky shape.

Both the first abrasive grains 4 and the second abrasive grains 5 protrude from the plating layer 3. That is, at least part of the first abrasive grains 4 and at least part of the second abrasive grains 5 both protrude outwardly from the surface (outer surface) of the plating layer 3. The amount of protrusion of the first abrasive grains 4 is larger than that of the second abrasive grains. The amount of protrusion denotes an average height of the abrasive grains protruding outwardly from the outer surface of the plating layer 3. As illustrated in FIG. 1 , a tip (position) of each of the first abrasive grains 4 (or second abrasive grains 5) farthest away from the base 2 is a protruding end 41 of a first abrasive grain 4 (or protruding end 51 of a second abrasive grain 5). The protruding ends 41 of the first abrasive grains 4 are located farther away from the base 2 (i.e., the outer surface of the plating layer 3) than the protruding ends 51 of the second abrasive grains 5 are.

In the electrodeposition whetstone 1, a first virtual plane V1 created by the protruding ends 41 and a second virtual plane V2 created by the protruding ends 51 are defined. Since the amount of protrusion of the protruding ends 41 is larger than that of the protruding ends 51, the first virtual plane V1 is located on the outer side with respect to the second virtual plane V2. It is preferable that the average distance between the first virtual plane V1 and the second virtual plane V2 be equal to or shorter than a range R. The range R can be suitably set based at least on the grain size of the first abrasive grains 4, the grain size of the second abrasive grains 5, and the thickness of the plating layer 3. It is preferable that the range R increase in accordance with an increase in the thickness of the plating layer 3. It is preferable that the range R be defined as 6 μm or larger and 42 μm or smaller. In one example, if the first abrasive grains 4 are in a grit size of around 600, the range R is preferably around 6 μm. In another example, if the first abrasive grains 4 are in a grit size of around 50, the range R is preferably around 42 μm. As will be described later, with the electrodeposition whetstone 1 satisfying the range R, the life of the electrodeposition whetstone 1 can be prolonged.

The first abrasive grains 4 are arranged in the plating layer 3 so as to be separated from each other in the orthogonal direction. That is, a gap is created in the orthogonal direction between the first abrasive grains 4 arranged in the orthogonal direction. The second abrasive grains 5 are arranged in the gaps created by the first abrasive grains 4 in the orthogonal direction. For instance, the second abrasive grains 5 are arranged in gaps created in the orthogonal direction by the first abrasive grains 4 adjacent to each other in the orthogonal direction. The size of the gap (interval) between the first abrasive grains 4 is preferably 20 μm or larger. In this case, the second abrasive grains 5 serve as a bond coating of the plating layer 3. This can improve the strength of the electrodeposition whetstone 1, and can also increase the force of the plating layer 3 holding the abrasive grains. The abrasive grains are therefore prevented from coming off from the electrodeposition whetstone 1. In addition, the plating layer 3 is prevented from being scratched by the grinding chips. The life of the electrodeposition whetstone 1 can thereby be prolonged.

With the first abrasive grains 4 arranged as described above, the grinding sharpness of the electrodeposition whetstone 1 is improved. The present inventors consider the explanation for this as follows. When a certain first abrasive grain 4 grinds a grinding workpiece, the grinding workpiece is shaved and deformed by the certain first abrasive grain 4. If the first abrasive grains 4 are separated from each other in the orthogonal direction, it is highly probable that another first abrasive grain 4 will grind the workpiece after the workpiece is elastically recovered. As a result, the grinding effects upon the grinding workpiece will be increased, and the friction upon the workpiece will be reduced. That is, the grinding resistance acting upon the electrodeposition whetstone 1 from the contact surface between the electrodeposition whetstone 1 and the workpiece is lowered. Thus, effective grinding can be performed by the electrodeposition whetstone 1, and the grinding sharpness of the electrodeposition whetstone 1 is improved. Furthermore, with the grinding resistance reduced, it is possible to prevent burrs from being produced in the workpiece by the electrodeposition whetstone 1.

The second abrasive grains 5 arranged as described earlier elongate the life of the electrodeposition whetstone 1. The present inventors consider the explanation for this as follows. During grinding of the grinding workpiece with the first abrasive grains 4, grinding chips are formed. Since the amount of protrusion of the second abrasive grains 5 from the plating layer 3 is smaller than the amount of protrusion of the first abrasive grains 4 from the plating layer 3 as described above, these grinding chips are broken by the second abrasive grains 5 into still smaller grinding chips. This reduces damage to the plating layer 3 that tends to be caused by the grinding chips. Furthermore, with the grinding chips being small, clogging can be suppressed, which tends to be caused by grinding chips being stuck between abrasive grains. As a result, the scratching of the plating layer 3 of the electrodeposition whetstone 1 can be suppressed, which can prolong the life of the electrodeposition whetstone 1.

Next, the method of manufacturing the electrodeposition whetstone 1 according to the present embodiment will be described. FIG. 2 shows the steps of an exemplary method of manufacturing the electrodeposition whetstone 1 according to the present embodiment. The base 2 used for the electrodeposition whetstone 1 is manufactured with a commonly known method. The surface (outer surface) of the base 2 may be treated with blasting, masking, or the like. In a blasting treatment, the electrodeposition surface is treated by injecting particles onto the surface (electrodeposition surface) of the base 2. For instance, alumina abrasive particles may be used in the blasting treatment. In a masking treatment, portions other than the electrodeposition surface are covered. For instance, a waterproof tape may be used to cover the portions other than the electrodeposition surface. The first abrasive grains 4 are dispersed over the surface of the base 2. Next, the surface of the base 2 to which the first abrasive grains 4 are attached is plated with first plating (primary plating). The first plating may be electrolytic plating, examples of which include electrolytic nickel plating. In this manner, the first abrasive grains 4 are secured to the surface of the base 2. Here, excessive first abrasive grains 4 may remain between the first abrasive grains 4. In this case, the excessive first abrasive grains 4 need to be removed from the surface of the base 2. As a result, suitable gaps (intervals) can be maintained between the first abrasive grains 4 in the orthogonal direction. Removal of the excessive first abrasive grains 4 may be conducted by hand scrubbing. The dispersion of the first abrasive grains 4 and the primary plating may be performed after the base 2 is cleaned following the blasting treatment. This will increase the adhesion between the primary plating and the base 2.

Further plating (secondary plating) is performed upon the first abrasive grains suitably secured to the base 2. The secondary plating may be performed in a manner similar to the primary plating. For instance, electrolytic nickel plating is performed. The previously mentioned first plating layer 31 is formed through the primary plating and secondary plating. As a result, the first abrasive grains 4 are secured to the surface of the base 2 by the first plating layer 31, as shown in the top of FIG. 2 . The total thickness (average total thickness) obtained by adding the thickness of the primary plating and the thickness of the secondary plating can be suitably determined with reference to the grain size (average grain size) of the first abrasive grains. The average total thickness may be, for example, about 20% of the grain size of the first abrasive grains 4, or about 30% of the grain size of the first abrasive grains 4.

Next, as shown in the middle of FIG. 2 , the second abrasive grains 5 are dispersed so as to arrange the second abrasive grains 5 in the gaps created in the orthogonal direction between the first abrasive grains 4. The second plating (tertiary plating) is performed upon the first plating layer 31, the first abrasive grains 4, and the second abrasive grains 5. The second plating differs from the first plating. The second plating may be electroless plating, examples of which include electroless Ni—P plating. The previously mentioned second plating layer 32 is thereby formed. The thickness of the tertiary plating is preferably smaller than the thickness of the secondary plating. The thickness of the tertiary plating can be suitably determined with reference to the grain size of the first abrasive grains 4 and the grain size of the second abrasive grains 5. The thickness may be 6 Tim or larger and 72 μm or smaller. As described above, the plating layer 3 is completed by the primary plating, secondary plating, and tertiary plating.

After the completion of the plating layer 3, heat treatment is conducted upon the electrodeposition whetstone 1. As a heat treatment, a commonly used method can be suitably used. For instance, heat treatment at 350° C. may be performed. As a result, the electrodeposition whetstone 1 of the embodiment is completed, as illustrated in the bottom of FIG. 2 . With the electrodeposition whetstone 1 formed as described above, the distance (average distance) between the first virtual plane V1 and the second virtual plane V2 can be determined within the range R.

If the second plating layer 32 contains particles having a friction coefficient lower than that of the second plating layer 32, the plating solution for the tertiary plating may contain PTFE having an average particle size of 0.1 μm or larger and 1 μm or smaller in an amount of 5% by volume or more and 40% by volume or less with respect to the total volume of the plating solution. As the tertiary plating, Ni—P—SiC dispersion plating, hard chromium plating, electroless Ni—P plating, electroless Ni—B plating, or electroless Ni—W—P plating may be performed. In this case, heat is applied to the second plating layer 32 after the tertiary plating so as to cure the second plating layer 32. This improves the wear resistance of the electrodeposition whetstone 1.

As described above, in the electrodeposition whetstone 1 of the present embodiment, the first abrasive grains 4 protrude from the plating layer 3 outwardly in the thickness direction. The second abrasive grains 5 are arranged between the first abrasive grains in the orthogonal direction. The amount of protrusion of the second abrasive grains 5 are a smaller than that of the first abrasive grains 4 from the plating layer 3 in the thickness direction, and the second abrasive grains 5 have a smaller grain size than that of the first abrasive grains 4. This suppresses stacking of grinding chips between the abrasive grains, as discussed above, in the electrodeposition whetstone 1 of the present embodiment, thereby prolonging the life of the electrodeposition whetstone 1.

In the electrodeposition whetstone 1 of the present embodiment, the first abrasive grains 4 may contain at least one selected from the group consisting of diamond abrasive grains, CBN abrasive grains, and metal oxide abrasive grains. The second abrasive grains 5 may include at least one of diamond abrasive grains and CBN abrasive grains. In this manner, the grinding chips can be reduced in size more efficiently in the electrodeposition whetstone 1 of the embodiment, as a result of which the life of the electrodeposition whetstone 1 can be further prolonged.

In the manufacturing method of the present embodiment, the first abrasive grains 4 are secured to the base by the first plating, with gaps created between the first abrasive grains 4 in the orthogonal direction. In the manufacturing method of the present embodiment, a grain size of the second abrasive grains 5 being smaller than a grain size of the first abrasive grains 4 are arranged in these gaps in the orthogonal direction. In the manufacturing method of the present embodiment, the first abrasive grains 4 and the second abrasive grains 5 are secured by the second plating, which differs from the first plating, in such a manner that the amount of protrusion of the second abrasive grains 5 in the thickness direction is smaller than the amount of protrusion of the first abrasive grains 4. As a result, an electrodeposition whetstone 1 with a long life can be produced.

MODIFICATION EXAMPLES

In a modification example, a coating layer 33 may be formed in the electrodeposition whetstone 1 after the plating process is completed, as shown in FIG. 3 . In this case, the plating layer 3 of the electrodeposition whetstone 1 further includes the coating layer 33. The thickness of the coating layer 33 is not limited as long as both the first abrasive grains 4 and the second abrasive grains 5 protrude from the coating layer 33, as illustrated in FIG. 3 . The thickness of the coating layer 33 may be, for example, 0.1 μm or larger and 0.5 μm or smaller. In one example, the coating layer 33 is formed through electroless plating using a nickel solution to which a reducing agent is added. In another example, the coating layer 33 is formed through electrolytic plating using a nickel solution to which a reducing agent is added. In the electrolytic plating, the plating bath may be a Watts bath or a sulfamate bath. The Watts bath contains, for example, nickel sulfate, nickel chloride, and boric acid as major components. The sulfamic acid bath contains, for example, nickel sulfamate and boric acid as major components.

Similarly to the second plating layer 32, the coating layer 33 may include particles having a friction coefficient lower than that of the coating layer 33. In this case, the aforementioned plating solution for the tertiary plating is used as a plating solution for the coating layer 33. With the coating layer 33 formed on the electrodeposition whetstone 1 in this manner, the life of the electrodeposition whetstone 1 can be further prolonged. In this case also, the amount of protrusion of the first abrasive grains 4 is larger than the amount of protrusion of the second abrasive grains 5 in the electrodeposition whetstone 1. Thus, the same action and effects as those of the above embodiment can be achieved in this modification example.

In another example, if the second plating layer is formed by plating that contains at least one of PTFE and tungsten, the second plating layer may not always attain a sufficient thickness to secure the first abrasive grains 4 and the second abrasive grains 5; the second plating layer is therefore formed by plating that does not contain PTFE or tungsten. In this manner, the second plating layer can be formed up to a thickness sufficient to secure the second abrasive grains 5. Thereafter, the coating layer 33 is formed. The coating layer 33 will be formed with plating that contains at least one of PTFE and tungsten. With the second plating layer and the coating layer 33 formed in this manner, even if the second plating layer cannot be formed to have a sufficient thickness, the electrodeposition whetstone 1 can still exhibit the same effects as the case where at least one of PTFE and tungsten is contained.

In another modification example, a foundation layer 7 may be formed in the electrodeposition whetstone 1, as shown in FIG. 4 . In this structure, the electrodeposition whetstone 1 further includes a foundation layer 7. The thickness of the foundation layer is not particularly limited. The thickness may be, for example, 0.1 μm or larger and 1 μm or smaller. The foundation layer 7 is formed of a material containing at least a ferrous material, aluminum, Alloy 42, or a non-metal material. Examples of the ferrous material include a stainless-steel material and a cast material. Examples of the non-metal material include a non-ferrous material and a resin material. Examples of the non-ferrous material include carbon fiber reinforced plastic (CFRP).

If the electrodeposition whetstone 1 includes the foundation layer 7, plating suitable for the material of the foundation layer 7 is provided on the base 2 before the first abrasive grains 4 are dispersed on the base 2. In one example, the base 2 is cleaned after the surface of the base 2 is subjected to the blasting or the like, and then the foundation layer 7 is formed on the base 2. In this case, copper plating or nickel chloride plating may be adopted for the plating. The foundation plating may be formed by dry plating instead of wet plating, which uses a plating solution. As the dry plating, physical vapor deposition (PVD) or chemical vapor deposition (CVD) may be performed. With the foundation layer 7 formed on the electrodeposition whetstone 1 in this manner, the life of the electrodeposition whetstone 1 can be further prolonged. In this case also, the amount of protrusion of the first abrasive grains 4 is larger than the amount of protrusion of the second abrasive grains 5 in the electrodeposition whetstone 1. Thus, this modification example can achieve the same action and effects as those of the above embodiment.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

What is claimed is:
 1. An electrodeposition whetstone comprising: a plating layer; a base on which the plating layer is provided; first abrasive grains protruding from the plating layer; and second abrasive grains arranged between the first abrasive grains, the amount of protrusion of the second abrasive grains from the plating layer being smaller than the amount of protrusion of the average grain size of the first abrasive grains from the plating layer, and a grain size of the second abrasive grains being smaller than a grain size of the first abrasive grains, wherein: the plating layer includes a first plating layer provided on the base and a second plating layer provided on the first plating layer, the electrodeposition whetstone includes: a first virtual plane formed by a plurality of protruding ends of the first abrasive grains, and a second virtual plane formed by a plurality of protruding ends of the second abrasive grains, the first virtual plane is located outside with respect to the second virtual plane, a distance between the first virtual plane and the second virtual plane is equal to or smaller than a range determined based at least on the average grain size of the first abrasive grains, the average grain size of the second abrasive grains, and a thickness of the plating layer, and the range increases as a thickness of the first plating layer increases.
 2. The electrodeposition whetstone according to claim 1, wherein: a grain size of the first abrasive grains is 25 μm or larger and 300 μm or smaller, a grain size of the second abrasive grains is 10 μm or larger and 120 μm or smaller, the thickness of the plating layer is 40% or larger and 80% or smaller of the average grain size of the first abrasive grains, and the range is 6 μm or larger and 42 μm or smaller.
 3. The electrodeposition whetstone according to claim 1, wherein: the first abrasive grains are separated from each other, and the second abrasive grains are respectively arranged in a gap between the first abrasive grains.
 4. The electrodeposition whetstone according to claim 3, wherein a size of the gap between the first abrasive grains is 20 μm or larger.
 5. The electrodeposition whetstone according to claim 1, wherein: lower ends of the first abrasive grains are at a boundary between the base and the first plating layer, and lower ends of the second abrasive grains are at a boundary between the first plating layer and the second plating layer.
 6. The electrodeposition whetstone according to claim 1, wherein: the first abrasive grains include at least one selected from a group consisting of diamond abrasive grains, CBN abrasive grains, and metal oxide abrasive grains, and the second abrasive grains include at least either one of diamond abrasive grains and CBN abrasive grains.
 7. The electrodeposition whetstone according to claim 1, wherein the plating layer includes at least one selected from a group consisting of polytetrafluoroethylene and tungsten.
 8. A manufacturing method comprising: securing a plurality of first abrasive grains to a base by a first plating layer, with gaps formed between the first abrasive grains, and forming a first virtual plane by a plurality of protruding ends of the first abrasive grains; arranging second abrasive grains in the gaps, a grain size of the second abrasive grains being smaller than a grain size of the first abrasive grains; and securing the first abrasive grains and the second abrasive grains by second plating different from the first plating layer in such a manner that the amount of protrusion of the second abrasive grains is smaller than the amount of protrusion of the first abrasive grains, forming a plating layer from the first plating layer and the second plating layer, and forming a second virtual plane by a plurality of protruding ends of the second abrasive grains, wherein: an average distance between the first virtual plane and the second virtual plane is equal to or smaller than a range determined based at least on an average grain size of the first abrasive grains, an average grain size of the second abrasive grains, and a thickness of the plating layer, and the range increases as a thickness of the first plating layer increases.
 9. The manufacturing method according to claim 8, wherein: the first plating layer is electrolytic plating, and the second plating layer is electroless plating.
 10. The manufacturing method according to claim 9, further comprising: separating the first abrasive grains from each other, and arranging the second abrasive grains in the gaps between the first abrasive grains.
 11. The manufacturing method according to claim 8, wherein the second plating layer contains at least one selected from a group consisting of polytetrafluoroethylene and tungsten. 